Knife sharpener



Sept. 4, 1962 J, BURG-.Ess 3,052,068

,KNIFE SHARPENER Filed Nov. 9, 1959 3 Sheets-Sheet 1 L wggm J. BURGESSKNIFE SHARPENER Sept. 4, 1962 5 Sheets-Sheet 2 Filed Nov- 9. 1959 j@ leSept. 4, 1962 J. BURGl-:ss 3,052,068

KNIFE SHARPENER Filed Nov. 9, 1959 5 Sheets-Sheet 5 IN V EN TOR.facysozz z/f e615* United States Patent Delaware Filed Nov. 9, 1959,Ser. No. 852,922 12 Claims. (Cl. 51-59) This invention relates to =knifeSharpeners, more particularly for household use for sharpening kitchenknives and the like, and aims to provide a simple and efficient deviceof this class that may be operated partly by manual and partly byelectrical means. This application is a continuation in part of JacksonBurgess application Serial Number 771,407, filed November 3, 1958, nowabandoned.

The invention contemplates a light, compact article that may be held inone hand while the knife blade is drawn therethrough with the otherhand. I'Ihe abrasive honing member is driven by a self-containedvibrating motor.

A particular object is to provide a knife Sharpener having an abrasivebody arranged to reciprocate in a direction crosswise of the edge of theknife and wherein the stroke toward the knife is the cutting stroke madeunder appropriate pressure between abrasive and blade, while theabrasive body is returned without substantial cutting effect. Anotherobject is to provide means for continuously changing the position of theabrasive body so that the portion thereof in contact with the knifeblade is continuously changed and wear is thus distributed to alluseable surfaces of the abrasive.

The foregoing and other objects and advantages will be apparent from thefollowing description, taken together with the accompanying drawingsshowing illustrative embodiments of the invention, in which drawings-FIGURE 1 is a perspective view showing the use of the device;

FIGURE 2 is an enlarged side elevational view thereof;

FIGURE 2a is a diagrammatic view of an abrasive cone;

FIGURE 3 is a plan View;

FIGURE 4 is a fragmentary side elevational view, partly in section onthe line 4 4 of FIG. 3;

FIGURE 5 is a fragmentary end elevational View;

FIGURE 6 is a cross-section taken on the line 6-6 of FIG. 4;

FIGURE 7 is another cross-section taken on the line 7-7 of FIG. 4;

FIGURE 8 is a more complete sectional view similar to FIG. 4 showing theoperating vibratory motor;

:FIGURES 9 and 10 show a modification; FIG. 9 being a plan section takenon the line 9 9 of FIG. l0; and FIG. 10 being a fragmentary verticalsection taken on the staggered line 10-10 of FIG. 9, the cones, however,being shown in elevation;

FIGURE 1l shows a further modification;

FIGURE l2 is a side elevational view, partly broken away and in section,showing an alternative arrangement of the knife Sharpener;

FIGURE 13 is a cross-sectional view similar to that of FIG. 8 andshowing a further modification of the invention, and

FIGURES 14, 15 and 16 are detailed views of the Sharpener-drivingmechanism, FIG. l5 being taken at line 15-15 of FIG. 14.

Referring in detail to the illustrative constructions shown in thedrawings and turning first to that of FIGS. 1 to 8 inclusive, inaccordance with the present invention the numeral 1 indicates a casinghaving a bifurcated top 2, the casing being advantageously made ofmolded complementary halves of a light-weight non-metallic initiallyplastic material secured together as by screws 2a and having an outlet1a for an electric cord 1b. The space between the bifurcations 2 of thecasing is partly closed by an inverted U-shaped metallic guard member 3that has out-turned ends 3a that may be snapped into the recesses 3b inthe ends of the case adjacent the bifurcations 2 to hold the guard 3 inposition by its own resilience. The guard 3 conforms to the profile ofthe casing top 2 and has therein closely adjacent slots 4 and 5 that arein parallel planes parallel to the axis of a honing member 6. In thisinstance the honing member 6 is conical and is mounted on a stud 6a(FIG. 8) of a thirnble '7 that in turn is carried on the upper end of arotatable spindle 8. The thirnble 7 has an axial recess 7a to receivethe upper end of the spindle 8 to which it is non-rotatively secured asby a set screw 9.

Each casing bifurcation 2 has an interior integral partition 10 moldedtherewith, these partitions extending toward each other and abutting attheir lower ends as at 10a but at their upper ends spaced apart as at10b (FIG. 7) so as to provide a slot of a width corresponding to theoverall width of the slots 4 and 5 in the guard 3. The proximate edges10c and '10d of the slot 10b are flush with the edges 4a and 5arespectively (FIG. 5) of the slots 4 and 5 in the guard 3 and all ofthese edges are in parallel planes that intersect the cone 6 on oppositesides thereof. That is to say, edges 4a and 10c are in one plane andedges 5a and '10d are in another plane. The included angle defined bythe cone 6 is preferably thirty-five degrees so that the angle ofincidence of the plane of a slot edge 4a and 10c, and correspondingly ofa slot edge 5a and 10d, is seventeen and one-half degrees with respectto the surface of the cone. An angle of seventeen and one-half degreesis substantially that of the knife edge 11 of a kitchen knife 12illustrated in FIG. 1.

When the knife blade 12 is inserted in one of the slots 4 or 5 of theguard 3, say first in the slot 4 as shown in FIGS. 1 and 6, it can bepushed down into contact with the cone `6, the slot 4 being wide enoughto receive the blade 12. Partitions 10 and outer edges 4a and 5a of theslots act as guides to hold the blades at the proper angle against thecone. If desired, only a single slot having side edges 4a and Sa may beprovided, since the necessary guiding surfaces would thus be present.Electrical means here represented by the vibrating motor 13 are providedfor reciprocating the cone 6 across the knife blade edge 11 while theknife is so held and while at the same time the knife is manually dra-wnlongitudinally through the slot 4, thus honing the blade edge along itslength. After sharpening one side, the blade is inserted on the otherside of the cone, as in slot 5, and the action repeated to sharpen itsother side. r

The vibrating motor =13 is shown in FIG. 8 and as there illustratedembodies a coil 13a `and core 13b and an armature 14 held at one end bya clip 15 and free to vibrate at its other end 16 toward and away fromthe magnetizable core 13b under the influence of an alternating electriccurrent led to the motor by the electric cord 1b. The spindle 8 at itslower end 18 is preferably dome shaped and abuts against the free end 16of the armature 14. At each half cycle of the excitation of the motorcoil 13a, the core 13b is magnetized and attracts to it the armature 14,which thereupon pushes the spindle 8 in a direction outwardly of thecasing '1 and axially of the spindle. As the current dies between halfcycles, the spindle 8 and with it the free end of the armature i-s movedin the opposite direction by a compression coil spring 19 encircling thespindle 8 between a pair of spacedapart bearing members 20n and 21 onthe spindle. Since with a sixty cycle current, for example, there willbe one hundred and twenty pulsations, the latter number of cycles ofreciprocation of the spindle 8` will occur, and a very rapid honingaction is accomplished. At one end the spring 19 bears against thebearing 20 and at its other end again-st a collar 2.2 fixed on thespindle 8. Bearings 20 and 21 are desirably of a `lubricous .materialsuch as molded nylon.

Further, in accordance with the present invention the spindle 8 not onlyreciprocates in the bearings but is also free to rotate therein with thecone 6 under the inliuence of the knife blade as the latter is drawnlongitudinally through the slot 4. The dome-shaped end 18 of the spindle8 where it bears against the armature permits rotation of the spindlewith a minimum of friction. Thus, continually different surface areas ofthe cone 6 are presented in honing action to the knife blade edge 11.The guides 10 assist in hol-ding the knife blade against the cone togive a rotative action to the cone while it is being reciprocated by themotor 13.

The amplitude of stroke of the motor armature 14, and consequently ofthe spindle 8, is adjustable by a spring abutment 23 that is mounted ina cylinder 24 carried within the casing 1. A screw 25 in cylinder 24 isprovided for compressing or relaxing the spring 23 and has a kerfed head26, for a screw driver or the like, accessible on the exterior of thecasing 1. Through a mating opening therein, the spring abutment 23 alsoprovides a cushion for the armature in its movement under the influenceof the spring 19.

In the form of the invention shown in FIGS. 9 and 10, the guard 27,otherwise similar to the guard 3, has only a single central slot 28therein which registers with a central slot 29V formed ybetween theguide partitions 30 in the bifurcated head 31 0f the casing 32. Here,the spindle 33 has affixed to its outer end an obliquely dis- 4posedcross yoke 34 rigidly secured thereto at 35. At each end of the crossyoke 34 there is a perforation for 'receiving the shank 36` with athimble 37 that carries a conical honing member 38. Rotation of thespindle and cross yoke must be prevented by suitable means, as byproviding a square spindle and bearing or, as here shown, by a stud 39that depends from the cross yoke and enters a recess 40 in the adjacentface of the casing 32. The shanks36 are held in position on the crossyoke -by washers 41 and set screws 42, respectively. Each honing memberor cone 38 may rotate on its shank 36.

In the use of the form of the device shown in FIGS. 9 and 10, the knifeblade, which is indicated schematically at 43 (FIG. 9) need be insertedonly once, that is, into the slot 28 of the guard 27, and it is thenpushed downy between and into contact with both of the cones 38simultaneously, the staggered arrangement of the cones permitting `theknife blade to intersect the surfaces of both cones at the same timewhile the knife blade edge itself is sharpened on both sides at one timeby the reciprocating action of the spindle 33 under the influence of themotor 13, which causes a honing action of both cones 38 across the knifesimultaneously. At the same time, the cones 38 may rotate independentlyon the cross yoke 34, asY the knife blade is drawn longitudinallythrough the slot 28 to hone the blade edge along its length and topresent fresh' surfaces of the honing material to the knife blade edge.

In another modification shown in FIG. 11, the honing member is in theform ofV a wedge-shaped blockA 4 of inverted V-shape. This form ofhoning member might be used in place of the honing member 6 of FIGS. 1to 8, and in such case the knife blade is inserted alternately in theslots 4 and 5 to contact successively with the opposite tapered surfaces44a and 44b ofl the wedge 44. Here again, the edges 4a and 10c, and 5aand 10d, intersect the sides of the V-shaped block 44 respectively. Inthis instance the wedge shaped block 44 cannot rotate as. the knifeblade is` drawn therealong, because of the parallelism therebetween, thelonger faces of the wedge .engaging the blade.

An exampleV of the knife Sharpener wherein means are provided forpositively rotating the honing member 6 during operation of the deviceis shown in FIGS. 13 through 16, the structure being otherwise similarto that above described. To effect rotation of the conical honing member6, a mechanical expedient that may aptly be termed a friction pawl andrachet is provided at the juncture of the extremity of lower end 18 ofspindle 8 with the end portion 16 of armature 14. The essentialrelationship of the armature and spindle driven thereby is that contactbetween the two members is made at or near the periphery of the spindleso` that longitudinal movement of the armature as it pivots about itsleft end (as seen in FIG. 13), being retained by clip 1S, results in theturning of spindle 8 about its axis to rotate the honing member 6. Toeffect this result, a Contact button or lip 50 is formed in the top edgeof armature element 16 by staking the metal at 51. The inclined surface(FIG. 15) thus provided engages the end 52 of the spindle at or near theperiphery thereof. Because the pressure between engagement surfaces oflip 51% and spindle 18 is different for the power and return strokes ofthe armature, the spindle is rotated during the power stroke, only, withthe result that the honing member is rotated in one direction tocontinuously change the grinding surface which is in engagement with theknife blade ybeing sharpened.

In the several examples of the Sharpener of the invention abovedescribed, the upward stroke of the spindle and abrasive member is thepower stroke of the motor and is, also, the cutting stroke. Analternative arrangement ofthe working parts is shown in the furtherexample of the invention illustrated in FIG. 12. In this form of theSharpener, the vibratory motor 13 is mounted with its armature 14a atthe top of the motor, as contrasted with the arrangement shown in FIG. 8wherein the armature is located underneath the motor. The power strokeof the motor of the device of FIG. 12 is, accordingly, downward, arelatively strong spring 46 being provided to return the armature to itsposition spaced from the field magnet structure of the motor preparatoryfor the succeeding power stroke. 'I'he spindle 8 is mounted forreciprocation in suitable bushings 20 and 21 which are, in turn,supported in sockets molded in body 1 of the Sharpener. The abrasive orhoning'member 6 is affixed at the top end of spindle 8 in the mannerabove described.

Spring means, such as leaf spring 47 is provided to bias the spindle andabrasive assembly downwardly sufiiciently to hold the spindle in contactwith the armature at all times. A suitable collar or other stop member48 is fastened to the spindle to receive the spring pressure for thispurpose. Alternatively, a coil compression spring may be insertedbetween the collar 48 and the body structureY above it. Regardless ofwhat form of` spring means are employed, the spindle and honing memberassembly is oated, in effect, between springs 47 and 46.

In the arrangement of the mechanism shown in FIG. 12, the cutting strokeis the moto-r return stroke rather than the power stroke. Otherwise, theoperation of this form of the invention is similar to that abovedescribed with reference -to other examples in that the knife issharpened -by reciprocation `of the conical or otherwise taperedabrasive head member.

By using a very stiff spring 46, it is possible to limit the movement ofthe armature on the power stroke to prevent striking lof the fieldmagnet` structure, thereby minimizing the noise created by operation ofthe motor. Form-s other than that shown by way of example of spring 46may be employed.

The honing members 6, 38 and 44 are advantageously mol-dedv of anabrasive material such as Carborundumf emery or the like, suitaibleinterlocking means being pro- Vided'between the abrasive material andits supporting thimble, suchas a roughening of the stud 6a indicated at45v (FIG. 8f).

It will be understood from the foregoing description of the Severalexamples of the invention that since the direction of reciprocation ofthe abrasive body is parallel with the width of the knife blade, and thecutting surface is inclined at an angle to the blade, upward movement ofthe abrasive body drives the abrasive Surface against and along theknife blade at the edge thereof, providing the necessary pressure andmovement for the abrasive cutting action. Correspondingly, downwardmovement of the abrasive member tends to draw the abrasive surface awayfrom the knife blade, with the result that very light cutting, if any,takes place in the direction away from the knife. Very little manuallyapplied pressure is needed to hold the knife in proper position for thesharpening operation.

When a conical abrasive or honing member is em* ployed, the sharpenedknife edge is -slightly serrated. Far from being undesirable, such anedge is more effective for cutting Ithan the usual s-traight edge.

The invention having been described, such changes may be made, includingfurther modifications or additions as fall within lthe Scope of theappended claims, without departing therefrom.

Invention is claimed as follows:

1. A knife Sharpener comprising a casing having a guide slot in the topthereof in approximately the principal vertical median plane of saidcasing, a spindle mounted for venticai lreciprocation along its axis inapproximately said median plane, a cross yoke carried by said spindle,and a pair of vertical conical honing members mounted upon vsaid crossyoke for free rotation about their respective conical axes, said conicalaxes being parallel to said spindle axis, and means for preventingrotation of said spindle about its axis, said honing member beingstaggered whereby to present overlapping inclined surfaces intersectingsaid plane of said guide slot.

2. A Sharpener for a knife having a blade and a cutting edge saidSharpener comprising: a casing; a member journaled in said frame forreciprocation along a line; a cutting device attached to saidreciprocating member, said device having a cutting surface positioned atan acute angle with respect to said line, whereby said surfacereciprocates lin a rst plane parallel to` said line; power meansoperatively connected to said member to reciprocate it; yand positioningmeans attached to said case to position said blade in a second planeparallel to said line with said edge intersecting said surface, and saidfirst plane and said second plane at approximately right angles to eachother.

3. The Sharpener of claim 2 wherein, said angularly disposed surface andsaid line define an included angle of approximately 171/2 4. A Sharpenerof claim 2 wherein, the cutting device is conical.

5. The Sharpener of claim 4 wherein, the conical device is mounted forfree rotation about its conical axis.

6. The Sharpener of claim 4 wherein, said Sharpener includes means forrotating the conical device about its conical axis.

7. The Sharpener of claim 4 wherein, said reciprocating member is aspindle mounted for rotation about said line and having an end spacedfrom said cutting device; said power means includes a vibratory motorhaving an armature, said armature being positioned to abut Said end ofsaid spindle near the periphery of Said spnidle to provide a frictionalpaWl and rachet arrangement for rotating Said spindle and Said cuttingdevice as Said cutting device is reciprocated.

8. The Sharpener of claim 2 wherein, Said cutting device is a V-wedgeshape.

9. The Sharpener of claim 2 wherein, there are a plurality of cuttingdevices positioned at opposite sides of Said piane.

10. The vSharpener of claim 2 including a second positioning means,parallel to and in juxtaposition with the rSt positioning means and atthe opposite side of said cutting device from said rst positioningmeans.

11. A knife Sharpener for a knife having a planar blade and a cuttingedge, said Sharpener comprising: a casing having means at Ithe topthereof to position said blade horizontally with the plane of the bladegenerally vertical and the edge downward and inside said casing; acutting device in said case and having a cutting surface below said edgeand extending upwardly an angle with respect to the plane of the blade;and power means mounted within said case and operatively connected tosaid device to move said device veitically with said surface contactinga Side of :said blade along said edge.

l2. The Sharpener Vof claim 11 wherein, said power means includes: aspindle journ'aled in said fr-ame for vertical movement and connected atits upper end to said device; a vibratory motor having a mov-ablearmature positioned to Contact the lower end of the spindle and urge thespindle up as the armature moves up; and resilient means between thespindle and `the casing to urge the spindle downwardly.

References Cited in the file of this patent UNITED STATES PATENTS2,024,860 Hobart et al Dec. 17, 1935 2,519,351 Calvert Aug. 2.2, 19502,691,252 Punton Oct. l2, 1954 2,706,852 Straub Apr. 26, 1955

